tolazoline

Tolazoline is a non-selective competitive α2-adrenergic receptor antagonist. It is a vasodilator that is used to treat spasms of peripheral blood vessels (as in acrocyanosis). It has also been used (in conjunction with sodium nitroprusside) successfully as an antidote to reverse the severe peripheral vasoconstriction which can occur as a result of overdose with certain 5-HT2A receptor agonist drugs such as 25I-NBOMe, DOB, and Bromodragonfly. ==History== Tolazoline was first used in the 1980s as an alternative reversal agent for xylazine. ==Use== Tolazoline is used in large animal medicine to reverse the effects of α2-adrenergic receptor agonists, typically xylazine. Large doses of intravenous tolazoline in cattle can cause hyperesthesia and opisthotonos and other routes such as intramusucular are preferred. ==Pharmacology== Tolazoline binds to the a2 adrenergic receptor at a ratio of 4:1, the lowest of all a2 adrenergic receptor antagonists. Tolazoline activates the imidazoline receptor.

IV tolazoline has slow elimination and a large distribution in the horse. ==References==